Starting to think about the questions science may need to consider to understand the ecosystems of the North East Kent European marine sites Diana Pound BSc, MSc, MIEEM Dialogue Matters, Wye, Kent. TN25 5BU Part 1 Our use of the natural environment will only be genuinely sustainable when we understand the functional limits of the ecosystems on which we depend and chose to live in. The focus of this paper is to start to think about the questions science may need to ask in order to understand the functional limits of one particular coastal and marine area, the North East Kent European marine site (NEKEMS) which stretches from Whitstable, on the Northern Coast round to Deal, on the Eastern Coast. It has been suggested in a separate paper in this report that the NEKEMS is well placed to begin to press forward with adopting the Ecosystem Approach. The Ecosystem Approach is described in that paper and is the primary framework for achieving sustainable development under the Convention on Biodiversity (see page 7). For the Ecosystem Approach to deliver its aims, ecosystems must be managed within the limits of their function. This requires: • an understanding of what an ecosystem is, • agreement amongst scientists and managers about the ecosystem/s under discussion, • developing understanding about the relationships and processes within these systems and the ecosystems structure and function, • developing a clearer idea of what the systems functional limits might be. Definitions of the word ‘ecosystem’ abound, including: • a functioning unit of biological life and natural processes, • a community of interdependent organisms together with the environment they inhabit and with which they interact (Dictionary of the Environment), • a dynamic complex of plant, animal and micro-organism and their non-living environment interacting as a functional unit (Article 2 of the Convention on Biodiversity). What is notable about these definitions is that none of them mention humans as part of the system. It is implicit that we are included within descriptive titles such as, ‘biological life’, ‘interdependent organisms’ or ‘animals’. However, we rarely use these titles to describe ourselves in these terms, and have tended to see ourselves as separate or outside ecosystems. When we do this, and ignore the need to maintain the functionality of the systems that provide our life support, we put both the system and ourselves at risk. 49 Before the structure and function of any given ecosystem can be understood, the spatial scale must be defined. Ecosystems can be defined at any spatial scale depending on the scale of the process – or the problem - under consideration. It is possible to talk about the ecosystem of a rock pool, a shore, a coastal cell, a regional sea or an ocean. Many ecosystems do not have readily definable boundaries because key processes eg water and nutrient supply originate ‘beyond any habitat or structural limit and operate at a range of scales’ (Laffoley and others, 2004). This is particularly the case with the sea where processes operate over large scales and distances. In practice, defining a particular ecosystem(s) is best done at a scale which is most appropriate in respect to managing human activities that form part of that system and depend on it. The focus of this paper is to start to think about the systems that operate in and around the NE Kent European marine site. The current boundaries of the NEKEMS have been defined based on the location of features of European importance and do not consider the ecosystem/s of which they are a part. For the purposes of managing NEKEMS from an ecosystem perspective, it will be necessary to decide whether the area defined on the current designations map is considered an ecosystem, part of an ecosystem or many ecosystems. Once the ecosystem(s) relevant to local decision-making have been defined, the next challenge is to begin to develop a sense of how resilient those systems are and what their functional limits might be. This concept accepts that ecosystems are dynamic. Traditionally, ecologists perceived all ecosystems as progressing along a continuum in a recognisable sequence with incremental changes occurring in a process of succession. Natural processes and feedback mechanisms would keep the system functioning within certain limits. It is now also accepted that if a system experiences sufficient natural or human induced disruption, these limits can be crossed, sudden changes occur, and a new state emerges. The model below aims to describe this concept visually. The circle represents the current state of the ecosystem as a ball that can role backwards and forwards between two points. With enough disruption the ball crosses the tipping point into a whole new state. Limits to current system New state New state The current state of the ecosystem Diagram 1: Model showing the idea that there are limits beyond which the processes in an ecosystem collapse and a new state results The implications of this are that scientists and managers need to start to work out what these limits might be, and what stresses or combination of stresses would take the system beyond the point of no return. Indicators can then be identified that provide early warning that the 50 system is getting close to its functional limits. Indicators will include species that are sensitive to particular parameters - a concept that is already familiar, particularly in the monitoring of water quality and nutrient levels. Some indicators will also need to be non- biological, such as working out the sediment budget in a coastal cell and the indicators of whether or not this is sustainable or headed towards cell fragmentation. Whilst the concept of indicators is not new, thinking about marine management from a holistic ecosystems approach is. There is an acknowledgement that we “need to shift the agenda from ‘what is there’ to ‘what does it do’” (Laffoley and others, 2004). However, it is not necessary for marine scientists to start from scratch. The science of landscape ecology may offer some helpful insights and models as the following quote shows: “Although applications in landscape ecology have traditionally been restricted to the study of terrestrial systems, the questions defining the science are equally relevant for marine systems. Indeed, knowledge of spatial pattern and the scales at which ecological processes take place is essential for effective management of marine environments. It is still unclear how the principles of landscape ecology can be translated into the marine environment, a three- dimensional milieu with physical and biological characteristics that often vary rapidly in space and time but it must start with bringing together researchers in the growing field of “seascape” ecology who are attempting to adapt the tools of landscape ecology to address ecological questions within marine and coastal systems”, (US International Association of Landscape Ecologists 2004 Symposium). Part 2 The second part of this paper seeks to borrow from the science of landscape ecology by considering some of the basic concepts, and begin to explore how they might apply and help in taking an Ecosystem Approach to the NEKEMS. Energy flows A foundation of the science of ecology is the consideration of energy flows. Part of considering functional limits must be to consider what the main energy flows are, whether or not they are in equilibrium, or whether more is going into the system or being depleted from it. At present the main flow of energy is from terrestrial ecosystems into marine systems in the form of nutrient runoff and wastewater. However, energy is also being depleted at higher trophic levels where over-fishing has led to the collapse of some fish stocks and as a consequence, fishing effort is now shifting down the food chain. really. That’s all sorted then………..quite simple 51 At a local level, work has yet to be done to understand the main energy flows in the ecosystem/s around north east Kent. Nutrient concentrations in the seawater are monitored and the Environment Agency is reviewing concentrations to see what effect they are having on the features of European importance (wintering turnstone and golden plover, chalk sea caves and reefs). However, the sensitivities and usefulness of these species and habitats as indicators for the health of the ecosystem as a whole is not known. Keystone species The concept of keystone species is best explained with reference to the game of Jenga, a game in which wooden blocks are stacked on top of each other in a solid column. The game is to remove the blocks that are not essential to the stability of the column and the loser is the one who removes one of the crucial blocks so that the whole column collapses. Keystone species are like those crucial Jenga Hey guys….. I’ve just heard we’re VIPs. blocks - they are vital for the functioning and We’re KEYSTONE species! resilience of the system, and have such a key role that their removal would lead to the collapse of the whole. Unlike Jenga, removing any components of the system unacceptably reduces its biodiversity. However, it is the keystone species that afford the system its stability. If the keystone species of the European marine site can be identified, and their niche requirements and sensitivities understood, then a way of maintaining the resilience of the system will be to maintain a viable and healthy population of these species. Metapopulations Metapopulations are the sum total of many local populations between which there is genetic mixing. Metapopulations provide resilience in a species gene pool and maximise the potential for adaptation to change. Isolated populations suffer the vulnerabilities of inbreeding with greater mutations, less resilience to disease or disaster, and loss of genetic diversity and adaptability.